Disaster-exposed youth, in comparison to adult samples, are at significantly greater risk for Posttraumatic Stress Disorder (PTSD), with symptoms often persisting for many months and years post-disaster. However, other disaster-exposed youth show resilience and rapid recovery without PTSD development. Efforts have been initiated to identify specific PTSD risk and resiliency factors;however, this work has relied largely on self- report strategies. Although useful in many circumstances, the sole reliance on self-report for identified PTSD risk and resiliency factors can be problematic. Thus, the development of innovative behavioral technologies that draw upon the methods of translational research and experimental psychopathology, and that assess specific risk and protective factors not easily or reliably measured through self-report, would be a valuable contribution to PTSD risk assessment. In the current study, we propose to develop and evaluate a state of the art comprehensive tool for PTSD risk assessment among disaster-exposed youth through the use of novel behavioral assessment tasks targeting two factors theoretically and empirically linked with PTSD (distress tolerance and risk-taking propensity), in combination with the use of other empirically identified disaster, child, and parent risk factors. If successful, this tool will help improve the understanding of more basic mechanisms underlying the development of PTSD in relation to disaster-related trauma, and potentially to other types of trauma, and also will likely aid in targeted early intervention development, modification, and implementation efforts. To accomplish these goals, this project will recruit a population-based sample of 3,000 disaster- exposed youth and their parents participating in an NIH-funded longitudinal, web-based intervention study (R01MH081056). Youth and parent participants will complete an initial phone-based, baseline assessment, where information regarding disaster exposure, other traumatic event experiences and incident characteristics, family-related variables, and PTSD and other mental health symptomatology will be gathered. Participants also will be asked to complete an additional web-based assessment following the baseline interview, which will involve both youth and parents completing novel computerized behavioral assessment tasks targeting distress tolerance and risk-taking propensity, as well as an additional self-report measure of trait anxiety. Phone-based interviews will be readministered at four- and twelve-months post-baseline to reassess PTSD symptoms. Sophisticated statistical procedures, including Receiver Operating Characteristics Tree methods, will be used to further examine the relation between the factors assessed and PTSD symptoms, to determine sensitive and specific cut-scores on the aforementioned tasks, measures, and variables for clinical decision-making, and to develop a decision algorithm that includes all significant PTSD predictors. Specifically, we seek to create an optimized, staged approach to PTSD risk assessment that balances accuracy against feasibility and costs to provide a practical, functional assessment battery that will generalize to multiple clinical settings. Given the high prevalence of disasters world-wide and the costly, debilitating impact of PTSD on disaster- exposed youth and their families, the proposed work is highly relevant to public health needs. Specifically, if successful in attaining the aims proposed for the current study, the sophisticated development of a PTSD risk assessment clinical tool would aid in the accurate and cost-effective identification of youth who are at greatest risk for PTSD. Such identification would help target post-disaster risk-reduction efforts and would likely reduce the incidence of full diagnostic PTSD and its associated costs and suffering.